SatNav Issues

In the post of the second day of the trip I mentioned the Samsung Tablet SatNav had a coronary leaving me with the ‘in-car’ navigation system.  This proved to be rather unsatisfactory as it has two major issues.  The first is the map is out of date.  I can live with this!  The second is the lack of detail.  If you zoom right in you can see the roads but on zooming out all the detail rapidly disappears.  The problem with this was I roughly knew where I wanted to go which meant I needed to zoom out.  That meant I couldn’t see places and roads. 

So what went wrong with the Samsung?  Well I think I’ve worked it out and may have resolved the problem.  When Jan told me the tablet had failed and wouldn’t recharge I suspect a faulty usb port on the tablet.  You may remember I used duct tape to hold the cable in the usb port.

July 2021 repair

After returning from the trip I plugged the tablet into the laptop to see if I could gain access.  The tablet would only do the boot cycle quickly showing the Samsung logo and the turning off.  Obviously it had a problem and I went off to clean all the fishing gear.

Returning in the evening I discovered the tablet would start.  The OSMAND navigation app also started.  Then I noticed a line of text at the bottom of the screen stating “charging slowly” and the tablet was also only 20% charged.  Maybe the usb port was faulty?

After removing all the duct tape I inspected and cleaned the usb port.  Not that much in the way of dirt appeared.  On plugging it back into the laptop I could again make it work and the navigation app would run.  However I still had the “charging slowly” message.

I then decided to charge the tablet from a 240V charger and after rummaging around in the boxes of “stuff that I might need one day” I found an old 240V 5W usb Apple charger.  That didn’t help and I still had the message.  More rummaging around and I found a 15W Apple charger.  No.. that didn’t solve the slow charging.  Finally I found a Samsung usb charger with UK pins.  Obviously an original.  Well that solved the slow charging.  Only the Samsung 240V charger worked.  Why?  After some internet searching I discovered Samsung has deliberately configured its tablets (and probably phones) to only slowly charge when connected to a device like a laptop.  This is to protect the laptop.  Samsung will allow the tablet to rapid charge if two of the usb pins are shorted (ie, connected together).  When the pins are shorted it prevents data from being transferred.  Obviously data can’t be transferred when the tablet is connected to a 240V charger which means the pins are shorted inside the charger.

Samsung UK 240V Charger

Now I know why the tablet was slowly charging when connected to the laptop. 

Then I realised what had actually happened was the tablet had slowly discharged on the first day of the trip despite being continuously plugged into the usb port on the dash.  The usb port on the dash had too lower power rating to keep up with the energy demand of the tablet and the navigation app.  By the second morning the battery was quickly fully discharged and the tablet was turning off only for a small amount of charge from the vehicle to reboot it.  Hence the coronary.

More research revealed the usb ports in vehicles frequently have a very low app rating.  Often as low as 500mA.  So despite being plugged into the vehicle the tablet battery was being drained faster than it could be recharged.

Now I know what the problem is I can source a solution.  I need a 12V usb charger that can produce sufficient power.  Back it the boxes of stuff you might need one day and I found one of these.

 

A dual usb port 12V cigarette socket charger rated at 2.1 Amps.  Unfortunately even this doesn’t produce sufficient power.  I’ve realised that whilst it is rated at 2.1A that is shared by both usb outlets.  A single outlet only produced 1.05A which isn’t enough.  I’ve found a 12V cigarette socket usb charger on eBay rated at 2A but the cost is over $30.  I have another solution.

I will fit a 12V to 5V usb converter to the vehicle dash.

This has a rated output of 5V 3A and was under $6 from eBay.  If my analysis is correct this will have sufficient power to charger the tablet whilst it is being used for navigation.  I’ll also no have a repeat of the outback navigation problem.

This has probably been a long and boring port.  but I’m rather pleased that I may have solved the problem of a tablet not recharging.  Ironically it appears there may never have been a problem with Jan’s Samsung Tablet.  She just had it plugged into a low power usb port.